The chemical name of carvedilol is ((±)1-(carbazol-4-yloxy-3-[[2-(o-methoxyphenoxy)ethyl]-amino]-2-propanol), the structure of which is shown as follows:

Carvedilol is a nonselective beta-adrenergic blocking agent with vasodilatory actions due to alpha-adrenoreceptor blockage. It is commonly used for the treatment of cardiovascular diseases, such as hypertension, congestive heart failure or left ventricular dysfunction following myocardial infarction. The anti-hypertensive actions of carvedilol result primarily from alpha-adrenoreceptor blockage, whereas the beta-adrenergic blocking action prevents the unwanted side effect, mainly reflex tachycardia, when used in the treatment of hypertension.
However, carvedilol has certain disadvantages in the treatment of medical conditions. For example, carvedilol is known to have solubility and stability problems and poor bioavailability. It is a weak base, so the solubility depends on the pH value. At pH values in the pharmaceutically relevant range of 1 to 8, the solubility of carvedilol in aqueous media increases from about 0.01 mg/ml to about 1 mg/ml. Furthermore, carvedilol presents low solubility in water, gastric fluid (simulated, TS, pH 1.1) and intestinal fluid (simulated, TS without pancreatin, pH 7.5). Carvedilol also presents a narrow absorption window. The relative absorption of carvedilol in the jejunum, ileum and colon is reported as 56%, 28% and 7% respectively. (See, e.g., WO2003/028718 and Nolte et al (Arzneimittelforschung 49(9):745-9, 1999)) Carvedilol's solubility and absorption limitations dictate immediate release commercial formulations for carvedilol that are administered twice a day. (See, e.g., Coreg® Prescribing Information)
Given the disadvantages and currently available carvedilol formulations, a need exists for a controlled release formulation of carvedilol that provides adequate bioavailability and extended release duration, allowing for a less frequent dosage requirement.